Cutting attachment for sewing machines



Dec. 3, 1929.

5 Sheets-Sheet l Filed April l1, 1927 Dec. 3, 1929. A. KRAsA 1,738,186

CUTTING ATTACHMENT FOR SEWING MACHINES Filed April 11, 1927 5sheets-sheet 2 C) 5 v 3mm A ./Uertfrasa.

331, @AAM 7 @LM 5 Sheets-Sheet 5 .fert Kras a.

A. KRASA Dec. 3, 1929.

CUTTING ATTACHMENT FOR SEWING MACHINES Filed April 11l 1927 Dec. 3,1929. A KRASA 1,738,186

CUTTING ATTACHMENT FOR SEWING MACHINES Filed April 11; 1927 5sheets-sheet k4 ,41beftmsawww.

Dec. 3, 1929. A. KRAsA CUTTING .ATTACHMENT FOR .SEWING MACHII-JES FiledApril -11I 1927 5 Sheets-Sheet 5 atto@ new;

Patented Da-n 3. 1929 UNITED STATES PATENT OFFICE ALBERT KRASA, OFCHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO ST. REGIS PAPERCOMIANY, F NEW YORK, N. Y., A CORPORATION OF NEW YORK CUTTING ATTACHMENTFOR SEWING MACHINES Application filed April 11,

My invention relates to a cutting attachment for a sewing machine, andhas as its object to provide a cutter particularly adapted toseverreinforcing tape between bags the mouths of which have been closed by aseam sewed through the tape. The object and details of my invention willappearmore fully as the description proceeds.

In the accompanying drawings, which form apart of this specification,Figure 1 is a side elevation of one form of apparatus embodying myinvention. Fig. 2 is a view of the apparatus shown inFig. 1, lookingfrom beneath. Figs. 3 and 3 are cross-sections on the lines 3-3 and 4-4,respectively, in Fig. 1. Fig. 5 is a cross-section on the line 5--5 ofFig. 3. Fig. 6 is a cross-section on the line@ 6--6 of Fig. 1. Figs. 7and 8 are details of 4portions ofthe clutch operating mechanism. Fig. 9is similar to Fig. 8, but shows the parts in a different position. Figs.10 to 15 are diagrammatic views of the` feed dogs and tape cuttingknives in different positions.

The apparatus disclosed shows my improvements applied to a'sewing headsubstantially like that disclosed in the co-pending application of A. M.Bates and myself, Serial No..616,37 2, whichihas eventuated in Patent'No. 1,625,r 81, issued April 26, 1927.

In the use of such apparatus as disclosed in that application, the topsof bags are fed in succession through the sewing machme, which appliesreinforcing tape to the s ides of the mouths ofthe bags andsews acontinu ous seam'through the reinforcing tape and the interposed wallsof the bag. Theimprovements forming the subject of this mventlon relateparticularly to means for severing the reinforcing tape betweensuccessive bags.

As will appear most clearly from Figs. 2

and 6, the tape is fed to position in front of the needle by tape guides21 and 22. Afterl the top 23 of onepbag has been completely sewed, theseam is continued through tape 24 beyond the edge of the bag to the topof the next bag 25; In order to disconnect the two bags from each other,it is necessary to cut the tape 24.

.In the apparatus disclosed, the tape is cut*` 50 by a stationary knifeand a movable knife.

1927. serial No. 182,664.

The stationary knife 26 is mounted in a knifecarrier 27 and projectsinto a suitable slot 28 in the throat plate 29, so as to be located at'one side of the path of the tape.

Movable knife 3() is mounted on the oppo- 55 site side of the tape in aknife carrier 31, which is reciprocable in suitable uides to move theknife 30 across the path o? the tape and sever it against fixed knife26.

The movable knife is actuated by carrier 31 60 which is connected by alink 32 to an arin 33 on a rock shaft 34. The other end of rock shaft 34carries an arm 35 connected by a link 36to a crank 37 on a crank-disc 38attached to the end of a clutch-shaft 39. As will be read' .65

ily seen, the reciprocating knife 30 is reciprocated once for eachrevolution of the clutch shaft 39.

The clutch-shaft 39 is parallel to the main shaft 4() of the sewingmachine. A pinion 41 .7o on the main shaft of the sewing machine mesheswith a clutch-gear 42 mounted loosely on the clutch-shaft.

Clutch-gear 42 comprises a disc portion 43 carrying gear teeth aroundits periphery 75 and 'cut away to form a recess 44 in which is mounted aflange 45 of clutch member 46. Gear 42 also comprises a collar 47 whichfits gver a sleeve 48 mounted on the clutch-shaft Pins 49 project fromclutch member 45 through slots 50 in disc member 43, and are connectedby springs 51 with pins 52 fast on disc member 43. Bumper members 53 aresecurely fastened bymean's of screws 54 `to g5 disc member 43. Thesebumper members are in position to contact pins'49 when the pins 49approach the limits of slots 50 away fromv Adjacent clutch member 46there is a cam e0 member v-55 which is secured rigidly to the clutchshaft. In the construction shown there is a notch 56 in the clutch shaftand a groove 57 in cam member 55, and a pin 58 driven through thisgroove and slot prevents a relative turning movement of the cam andshaft while permitting slight relative longitudinal adjustment.

Cam member 55 carries a disc cam 59. A

clutch dog 60 is pivoted at 61 to disc 59. Dog 10U shown, similar to pin88.

has a. tooth 62 at .one end in position to engage in either of twonotches 63 in the hub portion of clutch member 46. A spring 64 normallyurges dog 60 into engagement with clutch member 46. The dog is providedwith a projecting finger 65 which engages a trip pin 66 and holds thedog out of engagement with clutch member 46, except when the trip pin iswithdrawn.

A trip arm 67 is pivoted at 68 to a bracket 69 in position to have itsend 70 contact bags immediately beneath the seam as they are fed throughthe sewing machine. Another arm 71 extends from pivot 68 and forms witharm 67 a bell crank lever. A pin 72 in the end of arm 71 engages a fork73 on the end of an arm 74 fixed on a rock shaft 75. A member-76 isfixed in adjusted position and has a notch 77 the ends of which act aslimits for the movement of a pin 78` extending from arm 71. In this waythe extent of the rocking movements of arm 67 and shaft 75 are limited.i

At the other end of rock shaft 75 there are two arms 79 and 80. To theend of arm 79 there is pivoted a trip-releasing pawl 81. The free end ofthis pawl is provided with a notch 82 and normall rests against an arm83 of a rocking mem er 84 pivoted upon a horizontal pin 85. Pawl 81 hasa lug 86 to which there is attached a coiled spring 87 .the other end ofwhich is attached to a fixed pin l88.

To arm 80 there is pivoted a trip pawl 88 similar to trip pawl 81,except that pawl 88 is provided with a tooth 89 instead of notch 82. Theshape of tooth 89 is shownin dotted lines in Fig. 3.- The end of pawl 88rests against an arm 90 extending in an opposite direction from arm 83from the pivot of rocking member 84. A lugV 91 extends from! pawl 88andhas attached thereto a spring 92 whose other end is fixed to a pinnot Trip pin 66 is slidable in a hole 93 in a fixed bracket 94 whichsupports the clutch shaft and its attachments. l pin 66 there is agroove 95 in which there fits a member 96 projecting from an arm 97mounted on member 84 and extending at right angles to arms 83 and 90.Extending from the end of arm 97 in the opposite direction from member96 there is a lug 98. e e

Pivoted at 99 in bracket 94 there is a three-armed member 100. One arm101 of this member carries a cam roller 102 in engagement with theperiphery of 4disc cam 59. Another arm 103 of member 100 is connected bya strong spring 104 to a pin 105 fixed to In one side of member 109carries arcross-p'iece 111. At each end of cross-piece 111 there is apair of pins 112 between which pins a pawl 81 or 88 is positioned. A pin113 is adjustably fixed by a set screw 114 in position to limit theentrance of the respective pawl between pins 112.

In the construction shown, the' tape cutting knife 30 is adapted tooperate between the usual presser foot 115. and an auxiliary presserfoot 116. Presser foot 116 is preferably pivoted at 117 to a carrier 118for limited oscillation with respect to the carrier. It has an upturnedguiding toe 119.

It is preferable to employ a movable tapedepressing member 120 pivotedto the main presser foot and normally depressed by a spring 121. n.

`Knife 30 is constructed with a guide extension 121. The end ofextension 121 is beveled so as to slide from the end of fixed knife 26and bring the cutting edge proper 122 of the reciprocating knife intoshearing engpgement with the cutting edge of the fixed mi e.

It will be understood that rthe* mechanism shown comprises feed dogs123, 124 in suitable relation to the presser feet. Furthermore, in themechanism disclosed, there is a trimming knife 125 mounted in aslide-way in the feed dog carrier, in a manner similar to that disclosedin the previously mentioned application, and which does not need to befurther described in this case. l 1 The operation of the apparatus is asfolows: 1

Assuming the parts to be in the positions in which they are shown inFigs. 1 to 7, the clutch-dog is engaged by the trip pin and held out ofcontact with clutchmember 46. Gear 43 and clutch member 46 continue torotate about clutch-shaft 39 until the bag engaging -end 70 of arm 67has been closed. Then springs 87 and 92 pulling downward on the trippawls and the arms 79 and 80 to which they are attached, rock shaft 75and throw end of arm 67 past the edge of the closed bag.Y IVhen thisaction takes place, notch 82 of pawl 81 rests upon and drives downwardarm 83 of oscillating member 84. When member 84 is thus oscillated, arm96 is moved upward, as shown in Fig. 5, and' end 66 of the trip pin iswithdrawn from engagement with the clutch pawl. Thereupon the notchedend of the pawl is pressed against rotating clutch member 46 and engagesin the first notch which comes under it.

When the clutch-pawl is engaged in a notch in member 46, the member 46is arrested and stretches springs 51 until their tension starts rotationoffclutch member 46 and the pawl and member 55 therewith, or until thisresult is achieved by contact of pins 49 with abutment blocks 53.

Thereafter member 55 continues to turn and 130 drive clutch shaft 39with its crank until a complete revolution of shaft 39 has taken place.By this revolution rock shaft 34; is oscillated and cutting knife 30 isdriven downward and then drawn upward.

During the revolution of shaft 39, cam 107 operates in fork 108 to movethe fork downward and to raise pins 112, 113 upward, thereby moving thetrip pawls upward out of engagement with arms 83 and 90 of oscillatingmember 84. Arm 106 is moved to the position in which it is shown in Fig.8 beforetrip pawl 81 is released from arm 83, so that the end of arm 106temporarily blocks the downward movement of arm 96 by engaging lug 98thereon. However, immediately after the position in which the parts areshown in Fig. 8, roller 102 runs down on cam run 126-of cam 59 and movesarm 106 out of engagement with lug 98 and allows spring 127, attached toarm 90 and to fork 108, to oscillate member 84 and drivepin 66 downwardso .that its end projects in the path of the clutch-dog and throws itout of engagement with clutch member 46 when a revolution of shaft 39 iscompleted.

After pin 66 is thus projected, rotation of cam 107 returns pins 112 and4113 to their original positions and allows the trip pawls to againengage arms 83 and 90. If anotherV bag has `been fed to the machine sothat it contacts end 70 and oscillates shaft. 75 before the return ofthe trip pawls into engagement with arms 83 and 90, shaft 75 is heldwith arms 79 and 80 raised, as shown in Figs. 1, 3 and 5, so that thelower end of pawl 88-rests idly against arm 90, and tooth 82 of pawl 81just clears the top of arm 83. Thus the parts will be in the position inwhich they are shown in Figs. 1 to 6, and the clutch and cutter willremain at rest until this bag moves out of contact with end 70, whenend70 will drop and the movements described above will be repeated. If nobag is in contact with end 70 when trip pawls 81 and88 arere-engagedfwith arms 83 and 90, end 70 will remainlowered, and arms 79and 80 will b e held down by springs 87 and 92. Thedownward movement ofarms 79 and 80 is limited by the contact of pin 7 8 with the oppositewall of notch 77 from that with which it is shown in contact in Fig. 6,and the parts are so proportioned that, 1n

v this position, tooth 89 of pawl 88 is just below arm 90 with that armin the position in which it is shown in Fig. 5. This `allows pin 66'toremain in its stopping position as shown in Fig. 5, until end 70 israised. The raising of end 70 by the next bag sewed rocks shaft andraises arm 80 and pawl 88.

Since tooth 89 of pawl 88'l is hooked underneath arm 90, raising end 70raises arm 90 and' withdraws pin 66 out of the path of theI clutch dog,Thereafter the dog engages clutch member 46 and the cutting is repeatedas descrihedloove.

cutter cuts the tape between baas but once when there is just enoughspacebetween the bags to admit end 70, because end 7 0-is raised by thenext bag before the first cut is nompleted; but in all cases where thereis more than this minimum space between bags, the falling of 70 allowspawl 81 to descend and lower arm 83 and withdraw pin 66, thusinstituting a cut at the desired distance from the edge of the finishedbag, andthe raising" of end 70 by an oncoming bag raises pawl 88 and arm90 and againwithdraws pin 66, instltuting another cut at the desireddistance from the oncoming bag.

When the machine is being run at high speed, the clutch sh-aft and itsassociated parts acquire considerable momentum during the cuttingoperation. This momentum 4might continue the movements ofthe parts afterthe clutch-dog is disengaged if it were not for the provision of asafety device.

Cam 59 is provided with a socket 128 into which roller 102 fits when theclutch shaft i has arrived in position to result in the disengagement ofthe dog by pin 66. Spring 104 1s of sufficient strength to normallystop'y the movement of the clutch shaft and associated parts when roller102 enters notch 128; but when spring 104 is n'ot suflciently strong toovercome the momentum of the parts and prevent their turning beyond theintended point, roller 102 can ride up out of the notch only as far asshown in Fig. 9. At this point arm 106 engages projection 98 on arm 97.This forms apositive limit to the movement of the cam and clutch shaftasn long as pin 66 and consequently projection 98 remain in theposit-ions in which they are shown in Fig. 5, After the device isstopped, inthe position shown in Fig. 9, the action of spring 10ethrough roller 102 normally returns the cam Y to the intended restposition, with the roller resting in notch 128. j

It will be notedi that the gearing ratio is such that the shaft 39 makesone revolution 'While the main sewing machine shaft makes tworevolutions. In order to prevent interference of the cutting operationwith the feeding operatiomit is necessary that the cutting shall bevtimed to take place between successive movements of the feed dog. Theway in which this is accomplished is illustrated in I Figs. 10 to 15.The parts are so arranged that while the knife starts downward nearlngthe forward movement of the feed dog,

as indicated in Fig. 10, it does not contact the v material until thelimit of the feeding movement of the feedldog is completed, as shown inFig. 11. The cutting is thenaccomp1ished while the feed dog is moving tothe rear, as shown in Figs. 12, 13 and 14.-.

The projecting guide finger 121 of the movable knife vdoes not entirelyrecede` from the path of the material'until the feed dog has movedforward once more,as shown in Fig. 15, but this does' not interfere withthe movement of the bag and qits attached tape.

The tape may be drawn upward to. some extent by the upward movement ofthe cutting knife, as indicated in Fig. 14, but the tape-depressingmember attached to the -foot promptly returns the tape to its properposition after the cutter is raised.

Two notches are provided in clutch member 46 so that the clutch shaftand cutter is driven the first time that the main shaft of the sewingmachine arrives at proper position after the Itrip )ing of the clutch.

' It will'be seen th mechanism I have provided apparatus which will turnthe knife-moving shaft at only onehalf the speed of the main shaft ofthe sewing machine, and still the knife will not interfere with theproper4 feeding of the material through the sewing machine. Cutting ofthe tape at the proper interval after a bag has passed through thesewingmachine is insured byv this mechanism. If more tape thanisidesirable enters linto the seam between two successive bags, vthetape is again cut when another bag is presented. In other words, thetape is cut at the desired distance from each edge of the bag,regardless of the size of the bag or the distance apart of successivebags. In this way suicient extension of ythe tape to insure secureclosure is provided,

and unnecessary extension is avoided. The finished packages resultingfrom this closure apparatus are, therefore, uniform.

While the movement of the two feed dogs is approximately parallel witheach other, the dog-carrying member oscillates at-a polnt below the feeddogs, as viewed on Figs. 10 to 15. The result is that the feed dog 124moves a less distance to and from the work than does feed dog 123, and,therefore,.feed

dog 124 grips the work slightly sooner` than does feed.dog 123, andtends `to move 1t forward a slightly greater distance. This fact isutilized' in parting the tape. The rst feeding movement of the feed dogsafter the tape is severed tends to move the severed end slightly fartherthan the end still connected to the source of supply, so as to open up agap such' as shown at 129 on Fig. 15.

lVhile theapparatus is shown as particularly vdesigned for closingfilled bags, it will be understood that similar mechanism might beprovided for severing a reinforced seam between successive empty bags orother ar- Ves ticles; and while the cutter has been shown in connectionwith a particular type of sewing machine, it will be understod `that theform of the sewing machine to which it is attached may be modified asdesired without affecting the scope of the invention.

What I claim is: ff

l. In combination, a sewing device adapted to sew a continuous seamacross successive at by the above describedarticles, a cutter throughwhich the seam passes as it moves away from said device, and means toactuate the cutter and make one cut across' the seam a predeterminedJdistance in advance of the front edge of an article and to make one cutacross the seam a predetermined distance behind the rear edge of anarticle.

2. In combination, a sewing device adapted to sew a continuous seamacross a plurality of articles, and a seam cutter towards which the seammoves from said device, a trip in the path of the articles at one sideof the seam and adjacent the cutter, and connections from the tripoperating the cutter to make one cut across the seam a, predetermineddistance in advance of theforward edge of the article and to make onecut across the seam a predetermined distance behind the rear edge of anarticle.

3. In combination, a sewing device adapted to form a continuous seamacross a plurality of drticles, a seam cutter towards which the seammoves' from said device, a continuously operating source of power forthe cutter, a one-revolution. clutch connecting the source of power withthe cutter, and means actu' ated by the articles to close the clutchwhen the forward edge of an article approaches the cutter to apredetermined point and when the rear edge of an article has passed thecutter a predetermined distance.

4. In combination, a device adapted to sew a continuous tape to a seriesof bags, a cutter towards which the tape moves from the device,operating means for the cutter, a trip in the path ofthe bags at oneside of the tape, 'and connections whereby the cutter is actuated tomake one cut across the tape and seam sewed therethrough when the tripmoves from its normal position to a position resting against a passingbag and when the trip moves from its position resting against a passingbag to its normal position.

5. In combination, a sewing` device and a seam cutter towards which theseam moves from said device, a trip movable to two positions inaccordance with the passage-of work through the machine, and connections`be tween the trip and the cutter causing' the cutter to be actuatedonce for each movement of the trip from either one of its positions toits other position.

6. In combination, a sewing machine having a needle, a feed dog, and amain shaft operating the needle and feed dog in timed relation, a seamcutter in position to sever a seam sewed by the needle, a cutter shaftadapted to actuate the cutter to make one cut during one revolutionthereof, and gearing connecting the cutter shaft with the main shaft anddriving the cutter shaft one revolution for two revolutions of the mainshaft, the connection from the cutter shaft to the cutter being timed sothat the cutter crosses the seam during one idle stroke of the feed dog.

7. In combination, a sewing machine having a needle and feed dog, andmeans driving the needle and feed dog in timed relation, a reciprocatingcutter, and connections adapted to reciprocate the cutter once duringtwo reciprocations of the needle and feed dog, the connections beingtimed to move the reciprocating cutter into and out of the path of theseam during one idle stroke of the feed dog.

8. In combination, a sewing machine having a needle and feed dog, andmeans driving the needle and feed dog in timed relation, a reciprocating`seam-cutter, connections adapted to reciprocate the cutter once duringtwo reciprocations of the needle and feed dog, the connections beingtimed to move the reciprocating cutter into andout of the path of theseam during one idle stroke of the feed dog. a stationary cutter on theopposite side of the path of the scam from the normal position of thereciprocating cutter, and in position to have shearing co-operation withthe reciprocating cutter, and a guide finger extending from one side ofthe reciprocating cutter and adapted to guide the reciprocating cutterinto shearing relation with the stationary cutter.

9. A seam-cutter for a, sewing machine comprising a stationary knife onone side of the path of thescam, a reciprocating knife normally on theother side of the path of the seam, and a finger extending from one edgeof the reciprocating' knife towards, but not to, the stationary knifewhen the knives are separated, the reciprocating` knife being so mountedas to tend to abut the stationary knife, and the end of the finger beingbevelled to slide from the edge of the stationary knife and guide thecutting edge of the reciprocating knife into shearing relation with thestationary knife, and the edge of the reciprocating knife being beveledin the opposite direction from the end of the finger.

10. In combination, a sewing'machine having a main shaft, a cuttershaft, a seam-cutter driven by the cutter shaft, a one-revolution clutchon the cutter shaft driven by the `main shaft, saidone-revolution clutchcomprising a stop means, and said stop means comprising a cam having astop socket therein, 'a cam roller, a spring pressing the rolleragainst.

. the cam and into the socket at the stop position, a trip linger forclosing the clutch, and a member connected with the cam roller andengaging said finger before the roller is moved entirely out of saidsocket, when said finger is in open-clutch position.

11. In combination, a sewing machine having a main shaft, a seam-cutterattached to the sewing machine and having a cutter shaft, and drivingconnections between the main shaft and the cutter shaft, said drivingconnections comprising a limited lost motion connection and spring meanstending to turn the cutter shaft forward to the limit of said lostmotion.

l2. In combination, a sewing machine having a main shaft, a cutter and acutter shaft,

a member loose on the cutter shaft and connected to the main shaft to bedriven once during a plurality of turns of the main shaft, and a clutchdevice between said member and cutter shaft, one member of said clutchcomprising a dog and the other member of the clutch having therein anumber of notches equal to the number of turns which the main shaftmakes during one revolution of Said member, with any one of whichnotches said dog may co-operate. l

13. In combination, a sewing machine having a main shaft, a seam-cutterhaving a cutter shaft, a gear loose on the cutter shaft and meshing witha gear on the main shaft in two to one relation, and clutch meansbetween the gear and the cutter shaft, one of the members of said clutchcon'iprising a dog andl the other member having therein two oppositelydisposed notches with either of which the dog may co-operate.

14. In combination, a device for sewing a continuous seam throughsuccessive articles, a sea1n-cutter, a continuously operating drivingdevice for the cutter, a one-operation clutch for connecting the cuttertothe driving device for one operation of the cutter, a trip finger inthe path of the articles as they move 1Lpast the cutter, a rock shaft towhich the trip nger is attached, and two trip pawls connected tovsaidrock shaft, one of said pawls being` connected to trip the clutch whenthe shaft is rocked in one direction, and the other pawl being connectedto trip the clutch when the shaft is rocked in the other direction.

In testimony whereof, I have hereunto signed my name to thisspecification.

ALBERT KRASA.

